<!DOCTYPE html>
<html>
<head>
    <meta charset='UTF-8'>
    <title>定位-absolute</title>
    <style>
        body {
            color: white;
            padding: 10px;
        }
        div {
            background: deeppink;
            padding: 10px;
            width: 100px;
            height: 100px;
        }
        div.cus {
            background: dodgerblue;
            position: absolute;
            width: 50px;
            height: 50px;
            top: 30px;
            left: 30px;
            opacity: 0.8;
        }
    </style>
</head>
<body>
    <div>
        i am normal
    </div>
    <div class="cus">
        i am absolute
    </div>
    <div>
        i am normal
    </div>
</body>